The R's trailed thanks to goals from Kris Commons and James Bailey as the clock reached 90 minutes, but Patrick Agyemang and Jamie Mackie struck in time added on to secure a point.
Cardiff City were on course to take over at the top of the table thanks to their 2-0 win at Portsmouth. They took the lead through an own goal from Hayden Mullins and Jay Bothroyd made the win safe.
Ipswich Town are third, level with Cardiff and QPR on 10 points, after a 2-0 home victory against Bristol City. Tamas Priskin and Jason Scotland scored the goals that saw the visitors drop into the relegation zone.
Millwall returned to winning ways against Coventry City at the New Den. They took the lead through an own goal from Martin Cranie, with Liam Trotter and Steve Morison also scoring. Aron Gunnarson pulled one back for the Sky Blues, but could not prevent them losing 3-1.
Hull City fell apart on their travels once again, conceding in only the second minute at Doncaster Rovers. Martin Woods got that goal, with Billy Sharp and James Coppinger joining him on the scoresheet after Nick Barmby had levelled for the Tigers.
Middlesbrough continued their mediocre start to the season with a 2-0 loss at Barnsley. Jason Shackell and Adam Hammill scored for the Tykes.
Nottingham Forest and Norwich City drew 1-1 at the City Ground, with Dexter Blackstock putting Forest ahead and Andrew Crofts levelling for the Canaries.
Jean Calve's late goal gave Sheffield United a 1-0 home win over Preston North End, Gary Speed's first win since replacing Kevin Blackwell as Blades manager.
Swansea City also enjoyed a single-goal home success, with Scott Sinclair's strike seeing them past Burnley at the Liberty Stadium.
Richard Naylor's sixth-minute goal gave Leeds United a 1-0 success at Watford.
Leicester City dropped into the relegation zone after a 2-1 home loss to Reading - the Royals' first win of the season - in the late game.
Gylfi Sigurdsson and Matthew Mills scored for Reading, with Lloyd Dyer scoring for the Foxes.